Moved the chats of the BeyondFacts Lab to the embedded chat of assistants (#1203)

app/MindWork AI Studio/Chat/Embedded/EmbeddedChatTokenBudget.cs

@@ -0,0 +1,39 @@
+namespace AIStudio.Chat.Embedded;
+
+/// <summary>
+/// Decides how much room an embedded chat has left in the context of its model, see EmbeddedChat.ShowsContextWindow.
+/// </summary>
+/// <remarks>
+/// Meant for assistants whose requests carry long instructions, such as the guide of the BeyondFacts Lab: their
+/// conversations fill the context faster than an ordinary chat, and a model which loses the beginning of its context
+/// loses its instructions first. Therefore, the chat stops before.
+/// </remarks>
+public static class EmbeddedChatTokenBudget
+{
+    /// <summary>
+    /// From which share of the context on the chat warns.
+    /// </summary>
+    public const double WARNING_SHARE = 0.8;
+
+    /// <summary>
+    /// How many tokens the chat keeps free for the next message and its answer.
+    /// </summary>
+    public const int RESERVE_TOKENS = 4_096;
+
+    /// <summary>
+    /// Decides how much room a chat has left.
+    /// </summary>
+    /// <param name="tokens">What the conversation costs, with the system prompt, and the context of the model.</param>
+    /// <returns>The state of the budget.</returns>
+    public static EmbeddedChatTokenBudgetState Of(ConversationTokens tokens)
+    {
+        if (!tokens.IsKnown || !tokens.Window.IsKnown)
+            return EmbeddedChatTokenBudgetState.UNKNOWN;
+
+        var window = tokens.Window.DefaultTokens;
+        if (tokens.Tokens > window - RESERVE_TOKENS)
+            return EmbeddedChatTokenBudgetState.FULL;
+
+        return tokens.Tokens >= window * WARNING_SHARE ? EmbeddedChatTokenBudgetState.WARNING : EmbeddedChatTokenBudgetState.OK;
+    }
+}